Ambient light sensors may be widely used in many electronic appliances. For example, most LCD TVs (“Liquid Crystal Display televisions”) may utilize ambient light sensors to control the LCD (“Liquid Crystal Display”) screens according to the ambient environment. In addition, ambient light sensors may be widely used in portable devices. For similar reasons explained above, LCD screens for portables devices such as mobile phones, portable computers and tablets may also rely on ambient light sensors for automatic brightness control targeted to reduce power consumption. Another popular application for ambient light sensors may be cameras. Most cameras perform image processing on the images taken in accordance to ambient light.
One major component of ambient light sensors for detecting light may be photo-detectors. However, photo-detectors can only detect light intensity but cannot detect wavelength. This may be due to the reason that different light sources may produce similar brightness. Interposing various optical filters on ambient light sensors may enable wavelength detection to some extent. For example, by using several photo-detectors each covered by different filters such a red, green blue, cyan, magenta, yellow, and infrared filters, light of having such wavelengths may be detected by the respective photo-detectors.
However, different light sources may produce light having different wavelength components. If a special discrimination technique is available to detect the wavelength components of the ambient light, light sources may be identified more accurately. Therefore, a cost effective wavelength discrimination technique may be desirable for ambient light sensing. However, such technique may not only be used in ambient light sensors, but also other optical sensors such as camera chips, fiber optic sensors or some other applications that may need to identify wavelength of the source.